1. Field of the Invention
This invention relates to an improved fastener, and more particularly, to an improved fastener for fixing automobile interior components or electrical equipment to given panels.
2. Description of the Related Art
A conventional fastener for such a purpose is disclosed in Registered Similar Design 2 of Japanese Design Patent Publication No. 855669.
This conventional fastener is intended for fixing a trim board as a vehicle interior component, and consists of a head for retaining a trim board and a leg to be fitted into a mounting hole of a panel. The head has two retaining flanges spaced apart via a neck and a sealing flange. The leg has two resilient engaging walls extending in the axis direction with slits interposed therebetween. Upper ends of the engaging walls are in their entire surfaces connected to the sealing flange of the head, and lower ends of the walls are connected to one another.
In use, a trim board is retained between the retaining flanges of the head, and then the leg of the fastener is inserted through a mounting hole provided in a panel. The walls of the leg during insertion flex inwardly and pass through the mounting hole, and engage with the rim of the hole at their shoulders, thereby enabling fixing the trim board to the panel.
The conventional fastener has an advantage that a trim board can be fixed to a panel through final one-touch operation. However, when the leg of the fastener is inserted into a mounting hole of a panel, since the upper ends of the engaging walls each having a sectionally arc shape and extending in a curve radially about the axis of the leg are integrally connected in their entire surfaces to the sealing flange of the head, the engaging walls cannot provide sufficient flexibility on each side. This requires larger insertion force, preventing improvement in workability. In addition, when a mounting hole of a panel is a reversely punched hole, a resultant burr protruding to the insertion side further requires larger insertion force.
This invention was made to effectively solve the above problems of the conventional fastener.
According to a first aspect of this invention, there is provided a fastener comprising: a head for retaining a vehicle component; a leg to be fitted into a mounting hole of a panel, the leg comprising a plurality of resilient engaging walls extending in the axis direction with a plurality of vertical slits interposed therebetween; each resilient engaging wall having an upper end connected to the head; the resilient engaging walls being connected to one another at lower ends thereof; and a cut provided in a lateral direction in the upper end of each resilient engaging wall.
Thus in this aspect, since the lateral cut is provided in the upper end of the engaging wall connected to the head, when the leg of the fastener is inserted into a mounting hole of a panel, the cut allows the engaging wall to easily flex inwardly. This enables inserting the leg into the hole with smaller force, resulting in significant improvement in workability.
According to a second aspect of this invention, the cut is provided in a lateral direction on each side of the upper end of each resilient engaging wall.
Thus in this aspect, since the lateral cut is provided on each side of the upper end of the resilient engaging wall, which end is otherwise hard and does not easily flex inwardly, when the leg is inserted into a mounting hole, the engaging wall can flex to a much larger extent on both sides. This provides further improvement in workability and prevents the engaging wall from falling down or collapsing, ensuring secure and firm engagement of the leg.
According to a third aspect of this invention, the lateral cut provided on a thicker side of the resilient engaging wall has a depth larger than that of the lateral cut provided on a thinner side of the resilient engaging wall.
Thus in this aspect, the thicker part of the wall becomes more flexible due to the larger depth of cut, and the thinner part of the wall retains rigidity due to the smaller depth of cut, so that flexibility and rigidity are equalized on both sides of the wall. This prevents the wall from partially collapsing, and also from being partially shaved off by a burr of the rim of a reversely punched hole, thereby allowing the wall to flex evenly in a wider region with respect to the inner periphery of the hole, and resultantly to be inserted with smaller force. The wall then abuts against the inner periphery of the hole in a wider region, and can be even more sufficiently retained.
According to a fourth aspect of this invention, a fastener as set forth in the second aspect further comprising: a support wall provided between the resilient engaging walls, the support wall being connected to both the head and lower interconnected part of the resilient engaging walls; wherein, the lateral cut provided, with a perpendicular line to the support wall, passing through the axis thereof, as a center, on a larger width side of the resilient engaging wall in a direction along the support wall, has a depth larger than that of the lateral cut provided on a smaller width side of the resilient engaging wall.
Thus in this aspect, the wall on the larger width side is more flexible due to the larger depth of cut, and the wall on the smaller width side retains rigidity due to the smaller depth of cut, resulting in the effects as described above.
According to a fifth aspect of this invention, connected part of the upper end of each resilient engaging wall left between the lateral cuts provided on both sides has, with a perpendicular line to the support wall, passing through the axis thereof, as a center, a larger width on the larger width side of the resilient engaging wall in a direction along the support wall, than a width on the smaller width side of the resilient engaging wall.
Thus in this aspect, the wall on the larger width side becomes more flexible due to the larger depth of cut while being supported by the larger width part of the connected part, and the wall on the smaller width side retains rigidity due to the smaller depth of cut while being supported by the smaller width part of the connected part, thereby being equalized in flexibility and rigidity. The wall thus flexes evenly in a wider region with respect to the inner periphery of the hole of the panel, being able to be inserted into the hole with much smaller force. The wall also abuts evenly in a wider region against the inner periphery of the hole, being resultantly much more stably retained.
According to a six aspect of this invention, a fastener as set forth in the second aspect further comprising: a shoulder provided in an upper part of the resilient engaging wall, constituting a slope with a radius from the axis of the fastener increasing as being away from the head, the shoulder having different vertical positions across the resilient engaging wall; wherein, the lateral cut provided on a side where the shoulder is distanced larger from the head has a depth larger than that of the lateral cut provided on a side where the shoulder is distanced smaller from the head.
Thus in this aspect, the shoulder on the smaller distanced side has relatively high rigidity due to the smaller depth of cut, and engages with the inner periphery of the hole of the panel with sufficient strength after inserted into the hole and abutting on the inner periphery of the hole. The sufficient strength causes the wall to exert high stress at the shoulder. The shoulder on the larger distanced side has a radius from the axis of the fastener smaller than that on the other side, and that part is enhanced in flexibility due to the larger depth of cut, although the engaging strength of that part of the shoulder inserted into the hole of the panel and abutting on the inner periphery of the hole becomes slightly smaller. As a result, even when the fastener is under high temperature in a car in hot weather, for example, and has been used for a long time, the fastener is unlikely to creep or collapse, ensuring high durability.